RedcrabX – Quick Start Guide

Your first steps with the worksheet calculator  |  Version 1.0

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Table of Contents

• 1. The Worksheet Concept
• 2. The Workspace
• 3. Your First Calculation
• 4. Variables and Assignments
• 5. Using Functions
• 6. Function Panels Overview
  • General Math
  • Geometry & Trigonometry
  • Statistics & Finance
  • Matrix & Rotation
  • Electrical Engineering
  • Special Functions
  • Temperature Coefficients
• 7. Arrays and Matrices
• 8. Angle Mode: DEG vs. RAD
• 9. Output Format
• 10. Other Box Types
• 11. Keyboard Shortcuts
• 12. Example Calculations

1. The Worksheet Concept

RedcrabX is a worksheet calculator: instead of a single input line you work on a free-form canvas where each calculation lives in its own MathBox. Results are shown immediately as you type.

Key ideas:

• Each MathBox is one expression or assignment.
• The boxes are evaluated in the order in which they are defined; a variable defined in one box is available for use in all other boxes. If a variable is defined more than once (which should be avoided), the most recently defined value is used.
• The worksheet is saved as a file (.rcx) and can be reopened at any time.
• Additional box types (TextBox, PlotBox, ChartBox, ImageBox, LabelBox) let you document, annotate, and visualize results on the same canvas.

2. The Workspace

The main window is divided into three zones:

Opening a Panel

Click one of the ribbon buttons in the Functions group: Functions, Special, Business, Physics, Geometry, Electrics, or Temp. Coeff. Each button toggles the corresponding panel open or closed.

3. Your First Calculation

1. Click on a position on the workspace to create a new Mathbox at that position.
2. Click inside the box and type an expression, e.g. 2 + 3 * 4.
3. The result appears immediately to the right of the = sign: 14.
4. Press Enter to confirm and move focus away, or just click elsewhere.

2 + 3 * 4              =  14
100 / 4 - 7            =  18
2^10                   =  1024
sqrt(2)                =  1.41421356

4. Variables and Assignments

Use := to assign a value to a variable. Variable names are case-sensitive and may contain letters, digits, and underscores.

r := 5                 // assign radius
A := pi * r^2          // use it: A = 78.53981634
U := 230               // voltage
I := 10
P := U * I             =  2300      // power

Built-in Constants

5. Using Functions

Functions are called with parentheses: name(arg1, arg2, …). You can type a function name directly or click the corresponding button in a function panel to insert it at the cursor.

sin(30)                =  0.5         // DEG mode
sqrt(144)              =  12
log(1000)              =  3
abs(-7.5)              =  7.5
round(3.7)             =  4
max(3, 8, 2)           =  8

Nested Functions

sqrt(pow_ur(230, 50))  =  32.53 V    // voltage from power and resistance
round(pi * 1000) / 1000 =  3.142

6. Function Panels Overview

Each panel is a collapsible sidebar with function buttons grouped by topic. Click any button to paste the function name (and argument placeholders) into the active MathBox.

General Math Functions

Geometry & Trigonometry Geometry

Statistics & Finance Business

Matrix & Rotation Physics

Electrical Engineering Electrics

Full documentation: ElectricsGuide.html

Special Functions Special

Temperature Coefficients Temp. Coeff.

A read-only reference table of temperature coefficients α (1/K) for common metals, alloys, and semiconductors. Use the values together with resdrift(alpha=α, Rk=…, dT=…) from the Electrics panel.

7. Arrays and Matrices

Numeric Arrays

Enter a comma-separated list inside square brackets:

v := [1, 2, 3, 4, 5]
sum(v)                 =  15
average(v)             =  3
stdev(v)               =  1.58113883

Range Literals

Use the [start..end] or [start..end:step] notation to generate arrays without typing every value:

[1..6]           →  [1, 2, 3, 4, 5, 6]        // integer range, step = 1
[1..12:0.1]      →  [1.0, 1.1, 1.2, …, 12.0]  // 111 elements, step = 0.1
[0..10:2]        →  [0, 2, 4, 6, 8, 10]       // custom integer step
[5..1]           →  [5, 4, 3, 2, 1]           // descending range

Matrices

Rows are separated by semicolons:

A := [1, 2; 3, 4]      // 2×2 matrix
det(A)                 =  -2
inv(A)                 =  [-2, 1; 1.5, -0.5]
transpose(A)           =  [1, 3; 2, 4]

Sets

Curly braces create a set (unordered, no duplicates):

A := {1, 2, 3}
B := {2, 3, 4}
union(A, B)            →  {1, 2, 3, 4}
intersect(A, B)        →  {2, 3}
card(A)                =  3

8. Angle Mode: DEG vs. RAD

Trigonometric functions respect the global angle mode, which can be toggled in the ribbon.

// DEG mode
sin(90)     =  1
cos(60)     =  0.5
atan2(1,1)  =  45      // degrees

// RAD mode
sin(pi/2)   =  1
cos(pi/3)   =  0.5
atan2(1,1)  =  0.7854  // radians (= π/4)

9. Output Format

Results are displayed with automatic precision. You can control the format:

10. Other Box Types

11. Keyboard Shortcuts

12. Example Calculations

Ohm’s Law and Power Dissipation

U  := 230            // supply voltage [V]
R  := 47             // resistance [Ω]
I  := U / R          =  4.89361702   // current [A]
P  := pow_ui(U, I)   =  1125.53 W   // power with unit

Statistics on a Measurement Series

data := [12.3, 11.8, 13.1, 12.7, 11.5, 13.4, 12.9]
average(data)        =  12.52857
stdev(data)          =  0.67737
median(data)         =  12.7
iqr(data)            =  1.05

Right Triangle

a := 3               // leg a
b := 4               // leg b
c := hypot(a, b)     =  5            // hypotenuse
alpha := atan2(a, b) =  36.86990°   // DEG mode

Wire Resistance and Voltage Drop

rho := 1.72e-8       // Cu resistivity [Ω·m]
l   := 50            // one-way length [m]
A   := 2.5e-6        // cross-section [m²]
I   := 16            // load current [A]

dU  := voltdrop(rho, I, l, A, 0)    =  11.01 V
dU% := voltdropct(230, rho, I, l, A, 0) = 4.79 %

Temperature Rise of a Resistor

alpha := 0.00393     // Cu temperature coefficient [1/K]
Rk    := 100         // resistance at 20 °C [Ω]
dT    := 80          // temperature rise [K]

Rw := resdrift(alpha=alpha, Rk=Rk, dT=dT)        =  131.44 Ω
// reverse: find temperature from measured warm resistance
resdrift(alpha=alpha, Rk=Rk, Rw=131.44)          =  80 K

dB Conversion

// Power mode  –  db = 10 · log10(P1 / P2)
dbcon(P1=2, P2=1)        =  3.0103 dB   // level from two powers
dbcon(P1=2, db=3.0103)   =  1 W          // reference power P2
dbcon(P2=1, db=3.0103)   =  2 W          // input power P1

// Voltage mode  –  db = 20 · log10(U1 / U2)
dbcon(U1=2, U2=1)        =  6.0206 dB   // level from two voltages
dbcon(U1=2, db=6.0206)   =  1 V          // reference voltage U2

2×2 Matrix Inversion

A := [2, 1; 5, 3]
det(A)               =  1
inv(A)               =  [3, -1; -5, 2]
A * inv(A)           =  [1, 0; 0, 1]   // identity check

RedcrabX Quick Start Guide  —  further topics: MathBox Guide  |  Electrics Guide  |  Geometry Guide  |  Plot Guide  |  Chart Guide